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Journal of Agricultural Research 
Vol. XXXI, No. 8 
work of Davis, Daish, and Sawyer (9), and Davis and Sawyer (10), 
it was felt that these variations would be least in the morning. The 
adhering soil was carefully removed from the roots before they were 
washed. In order to prevent the drying out of the plants in trans¬ 
ferring them from the greenhouse to the laboratory, they were placed 
in a desiccator which had been converted into a moist chamber. 
For the freezing-point determinations, the plants were first dried 
of adhering moisture by blotting with filter paper, then ground in a 
mortar until they were reduced to a pulp. This was placed in cheese¬ 
cloth and squeezed, either by twisting and pressing with pestle or 
in a tincture press. With various comparison, no difference in the 
depression was noted. Chandler (4), Dixon and Atkins (13), Knud- 
son and Ginsburg (26), and Newton (33) have found it desirable to 
use high pressures in order to express the sap. This procedure seemed 
unnecessary, since in the first place the tissues at all times were young 
and hence not highly lignified, in which case it is always shown that 
the difference is small; in the second place, Knudson and Ginsburg’s 
(26) work shows that when lower pressures are used to express the 
sap, the results more nearly coincide with the plasmolytic method. 
Salmon and Fleming (35), working with older wheat, found it necess¬ 
ary to treat the material with toluene or chloroform. The age of the 
plant also reduces very much the undercooling as discussed by 
Harvey (21). 
Experiments were conducted to determine the effect of freezing 
this material before extracting the juice, as followed by Gortner and 
Hoffman (17 ). Comparisons were made with several sets of plants 
which were grown and treated in the same way in every respect, 
except that half of each portion was ground and extracted at once, 
while the other half was frozen for one and one-half hours before 
extracting. The material was placed in stoppered bottles. These 
were placed in quart thermos bottles containing a freezing mixture 
of salt and ice in the proportion which produces a temperature of 
12°C. below zero. 
Table I. — Depression of the freezing point of sap from plants which were frozen 
and from those not frozen , and the difference in each case 
Date 
Age 
of 
plants 
Depression 
when— 
Differ¬ 
ence (+) 
or (—) 
when 
frozen 
Date 
Age 
of 
plants 
Depression 
when— 
Differ- 
ence(+) 
or (-) 
when 
frozen 
Frozen 
Not 
frozen 
Frozen 
Not 
frozen 
November 17_ 
Days 
7 
9 
9 
0.467 
.470 
.360 
.360 
.430 
.425 
0.475 
.480 
.395 
.400 
.415 
.405 
—0.008 
-. 010 
-. 035 
-.040 
+.015 
+.020 
November 6_ 
Days 
13 
15 
0.407 
.400 
.495 
.480 
0.390 
.390 
.470 
.465 
+0.017 
+.010 
+.025 
+.015 
Nov. 19_. 
Nnv. 13 
Nov. a 
Average 
difference- 
+. 0045 
The differences indicate that freezing has no consistent effect in 
increasing the osmotic pressure of the cell sap, and that the cells are 
not made more permeable by both freezing and grinding than by 
grinding only without freezing. 
The 2-day-old seedlings formed a paste when ground, but not 
enough sap could be extracted from this paste to make the test. 
